#include <stdio.h>  
#include <math.h>  
int x[105], y[105];  
  
double getS(int i, int j, int k) {  
    double a = sqrt(pow(x[i] - x[j], 2) + pow(y[i] - y[j], 2));  
    double b = sqrt(pow(x[i] - x[k], 2) + pow(y[i] - y[k], 2));  
    double c = sqrt(pow(x[k] - x[j], 2) + pow(y[k] - y[j], 2));  
    double p = (a + b + c) / 2;  
    double S = sqrt(p * (p - a) * (p - b) * (p - c));  
    return S;  
}  
  
int main() {  
    int t;  
    if (scanf("%d", &t));  
    while (t--) {  
        int n;  
        if (scanf("%d", &n));  
        for (int i = 0; i < n; i++)  
            if (scanf("%d%d", &x[i], &y[i])) ;  
        double S = 0.0;  
        for (int i = 0; i < n; i++)  
            for (int j = i + 1; j < n; j++)  
                for (int k = j + 1; k < n; k++)  
                    S = S > getS(i, j, k) ? S : getS(i, j, k);  
        printf("%.1f\n", S);  
    }  
    return 0;  
}  